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Date: Wed, 17 Jun 2015 17:40:46 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Xiao Guangrong <guangrong.xiao@...ux.intel.com>
CC: gleb@...nel.org, mtosatti@...hat.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, dmatlack@...gle.com
Subject: Re: [PATCH v2 11/15] KVM: MTRR: sort variable MTRRs
On 15/06/2015 10:55, Xiao Guangrong wrote:
> Sort all valid variable MTRRs based on its base address, it will help us to
> check a range to see if it's fully contained in variable MTRRs
>
> Signed-off-by: Xiao Guangrong <guangrong.xiao@...ux.intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 3 ++
> arch/x86/kvm/mtrr.c | 63 ++++++++++++++++++++++++++++++++++-------
> arch/x86/kvm/x86.c | 2 +-
> arch/x86/kvm/x86.h | 1 +
> 4 files changed, 58 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index f735548..f2d60cc 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -345,12 +345,15 @@ enum {
> struct kvm_mtrr_range {
> u64 base;
> u64 mask;
> + struct list_head node;
> };
>
> struct kvm_mtrr {
> struct kvm_mtrr_range var_ranges[KVM_NR_VAR_MTRR];
> mtrr_type fixed_ranges[KVM_NR_FIXED_MTRR_REGION];
> u64 deftype;
> +
> + struct list_head head;
> };
>
> struct kvm_vcpu_arch {
> diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
> index cb9702d..c06ec13 100644
> --- a/arch/x86/kvm/mtrr.c
> +++ b/arch/x86/kvm/mtrr.c
> @@ -281,6 +281,52 @@ static void update_mtrr(struct kvm_vcpu *vcpu, u32 msr)
> kvm_zap_gfn_range(vcpu->kvm, gpa_to_gfn(start), gpa_to_gfn(end));
> }
>
> +static bool var_mtrr_range_is_valid(struct kvm_mtrr_range *range)
> +{
> + u64 start, end;
> +
> + if (!(range->mask & (1 << 11)))
> + return false;
> +
> + var_mtrr_range(range, &start, &end);
> + return end > start;
> +}
I think this test is incorrect; it is always true unless end overflows
to zero, which cannot happen because writing an invalid value to the
MSR causes a #GP.
Paolo
> +static void set_var_mtrr_start(struct kvm_mtrr *mtrr_state, int index)
> +{
> + /* remove the entry if it's in the list. */
> + if (var_mtrr_range_is_valid(&mtrr_state->var_ranges[index]))
> + list_del(&mtrr_state->var_ranges[index].node);
> +}
> +
> +static void set_var_mtrr_end(struct kvm_mtrr *mtrr_state, int index)
> +{
> + struct kvm_mtrr_range *tmp, *cur = &mtrr_state->var_ranges[index];
> +
> + /* add it to the list if it's valid. */
> + if (var_mtrr_range_is_valid(&mtrr_state->var_ranges[index])) {
> + list_for_each_entry(tmp, &mtrr_state->head, node)
> + if (cur->base < tmp->base)
> + list_add_tail(&cur->node, &tmp->node);
> +
> + list_add_tail(&cur->node, &mtrr_state->head);
> + }
> +}
> +
> +static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> +{
> + int index, is_mtrr_mask;
> +
> + index = (msr - 0x200) / 2;
> + is_mtrr_mask = msr - 0x200 - 2 * index;
> + set_var_mtrr_start(&vcpu->arch.mtrr_state, index);
> + if (!is_mtrr_mask)
> + vcpu->arch.mtrr_state.var_ranges[index].base = data;
> + else
> + vcpu->arch.mtrr_state.var_ranges[index].mask = data;
> + set_var_mtrr_end(&vcpu->arch.mtrr_state, index);
> +}
> +
> int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> {
> int index;
> @@ -295,16 +341,8 @@ int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> vcpu->arch.mtrr_state.deftype = data;
> else if (msr == MSR_IA32_CR_PAT)
> vcpu->arch.pat = data;
> - else { /* Variable MTRRs */
> - int is_mtrr_mask;
> -
> - index = (msr - 0x200) / 2;
> - is_mtrr_mask = msr - 0x200 - 2 * index;
> - if (!is_mtrr_mask)
> - vcpu->arch.mtrr_state.var_ranges[index].base = data;
> - else
> - vcpu->arch.mtrr_state.var_ranges[index].mask = data;
> - }
> + else
> + set_var_mtrr_msr(vcpu, msr, data);
>
> update_mtrr(vcpu, msr);
> return 0;
> @@ -350,6 +388,11 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
> return 0;
> }
>
> +void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu)
> +{
> + INIT_LIST_HEAD(&vcpu->arch.mtrr_state.head);
> +}
> +
> u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
> {
> struct kvm_mtrr *mtrr_state = &vcpu->arch.mtrr_state;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 2ffad7f..6574fa3 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -7379,13 +7379,13 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> {
> int r;
>
> + kvm_vcpu_mtrr_init(vcpu);
> r = vcpu_load(vcpu);
> if (r)
> return r;
> kvm_vcpu_reset(vcpu, false);
> kvm_mmu_setup(vcpu);
> vcpu_put(vcpu);
> -
> return r;
> }
>
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index aeb0bb2..0e4727c 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -162,6 +162,7 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt,
> gva_t addr, void *val, unsigned int bytes,
> struct x86_exception *exception);
>
> +void kvm_vcpu_mtrr_init(struct kvm_vcpu *vcpu);
> u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn);
> bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data);
> int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data);
>
--
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